The present invention relates to the field of Obstetrics and, in particular, it concerns a device for performing evacuation of the contents of the uterine cavity.
It is known that the termination of pregnancy by means of a medically induced abortion is a frequently performed procedure in the practice of Obstetrics and Gynecology. During the first 16 weeks of gestation, this procedure is generally performed by means of a "Dilatation and Curettage" (D+C) procedure. The procedure of D+C entails dilating the uterine cervix to a sufficient diameter as to allow for the passage of a suction tube through the cervix and into the cavity of the uterus. The contents of the uterine cavity (i.e. the embryonic tissue, also known as the "conceptus") is then evacuated by means of vacuum extraction.
As the viscosity of both uterine secretions and embryonic tissue increases with gestation, progressively larger suction tubes are required for the performance of vacuum extraction in more advanced pregnancies. If a suction tube of too narrow diameter is used, the tube will become blocked, and the conceptus will not be successfully extracted. In general, it is necessary to use a tube whose external diameter in millimeters is equal to the number of weeks of gestation of the conceptus. Thus, a D+C performed at 8 weeks of gestation typically requires the use of an 8 millimeter external diameter suction tube, while a D+C performed at 12 weeks requires that a 12 millimeter tube be used. As the suction tube has to traverse the cervical canal prior to reaching the uterine cavity, predilation of the cervix to the diameter of the suction tube to be used must be performed, prior to introducing the tube. This is typically achieved by means of the insertion and removal of Hegar dilators of progressively larger diameter. In addition, particularly in primiparous patients, the cervix is often "ripened" with sea-weed based pharmaceuticals for several days prior to performance of the D+C; so as to facilitate easier dilation of the cervix.
Performance of induced abortion by means of this standard method of D+C, however, suffers from several deficiencies:
1. It is necessary to dilate the cervix, possibly up to a diameter of 16 millimeters. This invasive process is intrinsically traumatic and painful, and may introduce infection. PA1 2. As the process of cervical dilation is painful, it is necessary to administer general anesthesia to the patient. As such, an anesthesiologist must be in attendance at all D+C procedures, and the patient is exposed to the risks and complications of general anesthesia. PA1 3. It may be necessary to hospitalize the patient, both for the purpose of pre-dilation cervical ripening, and for the purpose of post-anesthesia follow up. In its 1996 report, the CDC Center for Disease Control and Prevention reported an 11% hospitalization rate for purposes of performing D+C procedures. PA1 4. The positioning of the tip of the suction tube within the uterine cavity is performed in a blind manner, or under limited external ultrasound guidance. As such, there is a significant incidence of complications (approximately 5%) such as failure to extract the entire conceptus (necessitating a repeat procedure), perforation of the uterus, creation of a false track into the uterus through the cervix, and damage to the uterus resulting in sterility. PA1 5. As ultrasound visualization of the conceptus in a gravid uterus is only possible after 45 days of gestation, it is not possible to perform D+C under ultrasound guidance prior to this date. PA1 6. Due to the blind nature of the procedure, it is necessary for an obstetrician to undergo a lengthy period of training to acquire sufficient skill and experience to be able to perform a D+C safely and successfully. PA1 1. The blades of such devices are exposed, and may cause damage to the uterus. PA1 2. Such devices remove the detached tissue by suction only, and thus may become blocked by viscous embryonic tissue or secretions. PA1 3. Performance of a D+C using such a device would have to be done either as a blind procedure (which would be particularly dangerous due to the exposed blades of the device), or under endoscopic guidance (necessitating the introduction of a fiber-optic instrument into the uterine cavity, in addition to the tissue extraction device).
Alternative devices for achieving tissue extraction with the aid of suction are known in other medical sub-disciplines, particularly in the field of orthopedic surgery. Such devices combine a suction catheter with a mechanism, such as a moving blade, for detaching the tissue to be extracted from its surrounding tissue. Such devices, however, are designed to extract hard tissues, such as bone, under direct visualization, and thus are not suitable for use on soft tissues within the uterine cavity, for the following reasons:
There is therefore a need for a device and method for extracting embryonic tissue from the uterus under direct visualization without the need for extensive cervical dilation, and without the need to introduce a second, fiberoptic, instrument into the uterus.